DWQ-2025-004407

WASTE CHARACTERIZATION PLAN

KENNECOTT UTAH COPPER LLC
BLUEWATER 1 MAIN REPOSITORY

Scope

This waste characterization plan will be used to characterize the nature of any waste materials planned to be disposed of in the Bluewater 1 Main Repository. Wastes already placed in
the repository are representative of the Bingham Creek Tailings, previously provided.

As specified in Groundwater Discharge Permit #UGW350010, issued July 14th, 2010, the Bluewater 1 Main Repository may only accept tailings, sludge, soil and waste rock generated from
mining activities. No organic chemicals will be permitted in the repository, although minor amounts of organic matter (grasses, leaves, sticks, etc…) may unavoidably be mixed with the
large volume, low toxicity waste materials. This primary information will be supported by visual inspection and by a level of sampling and analysis appropriate to the extent and type
of waste deposit.

Objectives

The objectives of the Waste Characterization Plan are as follows:

Ensure, through knowledge and understanding of the waste genesis and visual inspection, that the waste materials do not contain synthetic organic chemicals;
Characterize the nature of total metals and inorganic metals in the waste;
Characterize the variability in composition of the waste with respect to total metals and inorganics; and
Characterize the leachability of metals from the waste.

Criteria

As noted above, the primary method used to characterize the waste material will be the identification and knowledge of the process and processes that generated the waste material. Specifically,
information regarding waste deposition patterns and potential migration pathways, as well as information supporting the hypothesis that only inorganic (i.e. no synthetic organic chemical)
wastes are present will be evaluated. The waste must also fit within a broad definition of tailings, waste rock, soil and sludge from mining activities.

The second criteria that will be used to determine character of the waste will be the area and vertical extent of the waste deposit and its heterogeneity. The criteria will be based
on visual inspection and sampling as necessary. The number of samples collected will be based on the size of the deposit, taking into account possibly variability with depth. In addition,
the homogeneity or heterogeneity of the waste will also be judged to adjust the number of samples to be collected and analyzed. The precise design of sampling grids and types and numbers
of samples will be developed and submitted to the Utah Division of Water Quality (DWQ) on a case-by-case basis; however, the following sampling plan provides a representative approach
for tailings and waste rock.

Approximately, the following number of grab or composite samples will be prepared and analyzed:

Estimated Waste Volume (cu yd) Number of Samples
<100 1-3
100-1,000 5
1,000-10,000 15
>10,000 20

The number of samples will be adjusted accordingly depending on the degree of heterogeneity of the waste. Composite samples will consist of a minimum of three sub samples.

Sampling Methods

Two types of samples may be collected, grab samples and composite samples. The choice of sample type will be decided based on knowledge of the waste and visual inspection for heterogeneity.
Grab samples will generally only be used for waste materials which are quite homogeneous, whereas composite samples will be used for more heterogeneous wastes. Based on the envisioned
analytical suit, each grab or composite sample will contain approximately five pounds of waste material. All sampling will be performed in accordance with the Standard Operating Procedures
in Kennecott Utah Copper LLC (KUC) Quality Assurance Standards. This includes the use of plastic sampling tools and appropriate decontamination methods. KUC’s Health and Safety Standards
will also be used for personnel protection.

Composite samples will be prepared by dividing the waste into approximately 100ft x 100ft grid. The grid size will be adjusted based on the extent of the waste deposit. A proportional
volume of waste material will be collected from the center of each grid to the full depth of the waste deposit. The individual grab samples will be accumulated in a large container until
the appropriate number of sub samples has been collected. Then material will be manually but thoroughly mixed until homogenized. A sub sample will be collected from the homogenized
mass for analysis.

Analytical Methods

Samples will be analyzed for total metals, total inorganics, and leaching characteristics. Since the waste will be placed in the Bluewater 1 Main Repository, and no organic waste will
be placed in this disposal facility, there is not a likelihood of generating organic acids which could solubilize metals. Therefore, the Toxicity Characteristics Leaching procedure (TCLP,
EPA Method 1311) is not appropriate for waste materials to be placed in the Bluewater 1 Main repository. The Synthetic Precipitation Leaching Procedure (SPLP, EPA Method 1312) is more
appropriate, and will be used as the principal method for assessing leachability. Nevertheless, both SPLP and TCLP methods will be performed on representative samples of the waste materials
so that a worst-case assessment can be made. Any waste failing TCLP is characteristically hazardous and cannot be placed in the Bluewater 1 Main Repository.

Tables B1 and B2 list the specific analytical methods which will be used as reference. All methods for metals and leaching characteristics are based on EPA Method SW-846. The methods
for conventional inorganics are also based on standard reference documents. The Practical Quantitation Limits (PQLs) are provided along with specific method references. All metals, except
mercury, will be analyzed through acid digestion and Inductively Coupled Argon Plasma (ICP). Mercury analysis will be analyzed by cold vapor atomic adsorption to ensure the attainment
of low detection limits.

Table B1. Standardized Preparation/Analytical Methods & Detection Limits for Analytes in Soils.

Total Metals Method Index Method Reference Practical Quantitation Limit (mg/kg) Arsenic 3050B 6010C 4 Barium 3050B 6010C 2 Cadmium 3050B 6010C 1 Chromium 3050B 6010C 2 Cobalt 3050B 6010C 1 Copper 3050B 6010C 5 Iron 3050B 6010C 1 Lead 3050B 6010C 3 Manganese 3050B 6010C 1 Mercury 3050B 7471A 0.10 Molybdenum 3050B 6010C 1 Nickel 3050B 6010C 1 Silver 3050B 6010C 5 Selenium 3050B 6010C 5 Zinc 3050B 6010C 5

Table B2. Standardized Preparation/Analytical Methods & Detection Limits for Leachable Metals in Soils.

EPA Method Method Index Method Reference Practical Quantitation Limit (mg/L) TCLP-1311 Arsenic 1311/3010A 6010C 0.1 Barium 1311/3010A 6010C 0.1 Cadmium 1311/3010A 6010C 0.01 Chromium 1311/3010A 6010C 0.1 Lead 1311/3010A 6010C 0.05 Mercury 1311/3010A 7471A 0.0010 Selenium 1311/3010A 6010C 0.1 Silver 1311/3010A 6010C 0.1
  SPLP-1312 Arsenic 1312/3010A 6010C 0.1 Barium 1312/3010A 6010C 0.1 Cadmium 1312/3010A 6010C 0.01 Chromium 1312/3010A 6010C 0.1 Lead 1312/3010A 6010C 0.05 Mercury 1312/3010A 7471A 0.0010 Selenium 1312/3010A 6010C 0.1 Silver 1312/3010A 6010C 0.1
NOTE: Method Index/Method reference
SW 846 “test Methods for Evaluating Solid Waste,” 3rd Edition, November 1986.

DWQ-2020-015190

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April, 2020 WASTE CHARACTERIZATION PLAN; APPENDIX B; Kennecott Bingham Canyon Mine and Water Collection System Page 0
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Appendix B Permit # UGW350010

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